Add labels implicitly for parser and ner

spacy/pipeline/_parser_internals/arc_eager.pyx

@@ -614,10 +614,22 @@ cdef class ArcEager(TransitionSystem):
         actions[LEFT].setdefault('dep', 0)
         return actions
 
+    @property
+    def builtin_labels(self):
+        return ["ROOT", "dep"]
+
     @property
     def action_types(self):
         return (SHIFT, REDUCE, LEFT, RIGHT, BREAK)
 
+    def get_doc_labels(self, doc):
+        """Get the labels required for a given Doc."""
+        labels = set(self.builtin_labels)
+        for token in doc:
+            if token.dep_:
+                labels.add(token.dep_)
+        return labels
+
     def transition(self, StateClass state, action):
         cdef Transition t = self.lookup_transition(action)
         t.do(state.c, t.label)

spacy/pipeline/_parser_internals/ner.pyx

@@ -126,6 +126,13 @@ cdef class BiluoPushDown(TransitionSystem):
     def action_types(self):
         return (BEGIN, IN, LAST, UNIT, OUT)
 
+    def get_doc_labels(self, doc):
+        labels = set()
+        for token in doc:
+            if token.ent_type:
+                labels.add(token.ent_type_)
+        return labels
+    
     def move_name(self, int move, attr_t label):
         if move == OUT:
             return 'O'

spacy/pipeline/transition_parser.pyx

@@ -132,6 +132,23 @@ cdef class Parser(TrainablePipe):
             return 1
         return 0
 
+    def _ensure_labels_are_added(self, docs):
+        """Ensure that all labels for a batch of docs are added."""
+        resized = False
+        labels = set()
+        for doc in docs:
+            labels.update(self.moves.get_doc_labels(doc))
+        for label in labels:
+            for action in self.moves.action_types:
+                added = self.moves.add_action(action, label)
+                if added:
+                    self.vocab.strings.add(label)
+                    resized = True
+        if resized:
+            self._resize()
+            return 1
+        return 0
+
     def _resize(self):
         self.model.attrs["resize_output"](self.model, self.moves.n_moves)
         if self._rehearsal_model not in (True, False, None):
@@ -188,9 +205,9 @@ cdef class Parser(TrainablePipe):
     def predict(self, docs):
         if isinstance(docs, Doc):
             docs = [docs]
+        self._ensure_labels_are_added(docs)
         if not any(len(doc) for doc in docs):
             result = self.moves.init_batch(docs)
-            self._resize()
             return result
         if self.cfg["beam_width"] == 1:
             return self.greedy_parse(docs, drop=0.0)
@@ -207,10 +224,6 @@ cdef class Parser(TrainablePipe):
         cdef StateClass state
         set_dropout_rate(self.model, drop)
         batch = self.moves.init_batch(docs)
-        # This is pretty dirty, but the NER can resize itself in init_batch,
-        # if labels are missing. We therefore have to check whether we need to
-        # expand our model output.
-        self._resize()
         model = self.model.predict(docs)
         weights = get_c_weights(model)
         for state in batch:
@@ -234,10 +247,6 @@ cdef class Parser(TrainablePipe):
             beam_width,
             density=beam_density
         )
-        # This is pretty dirty, but the NER can resize itself in init_batch,
-        # if labels are missing. We therefore have to check whether we need to
-        # expand our model output.
-        self._resize()
         model = self.model.predict(docs)
         while not batch.is_done:
             states = batch.get_unfinished_states()
@@ -314,6 +323,9 @@ cdef class Parser(TrainablePipe):
             losses = {}
         losses.setdefault(self.name, 0.)
         validate_examples(examples, "Parser.update")
+        self._ensure_labels_are_added(
+            [eg.x for eg in examples] + [eg.y for eg in examples]
+        )
         for multitask in self._multitasks:
             multitask.update(examples, drop=drop, sgd=sgd)